Some of the things you changed wouldn't have anything to do with this issue, specifically the "where to look" params. Presumably it won't hurt anything to have changed them.
Changing the quantities on those functions is a start, but you need to look at where they are called as well. As an example,
Code:
bool Client::DecreaseByID(int32 type, int8 amt)
has the potential to cause issues, although it is only called from Perl, and I didn't dig through any quest scripts to see if it is even used.
If you are able to narrow down specifically what you do to cause the problem it would probably help to narrow it down where in the code it might be occurring.